Learning Objectives

1. Name and describe key bone markings, their functions, and their role in the skeletal system using skeletal models, 3D digital tools and anatomical references.

1. Introduction

The surface features of bones vary considerably, depending on the function and location in the body. Each has its own unique story to tell. Bone markings are specific anatomical features on bones that serve important functions such as:

• Providing passages for blood vessels and nerves
• Creating articulation points between bones
• Serving as attachment sites for muscles, tendons, and ligaments

These features generally fall into three main categories:

• Openings
• Depressions
• Projections
  • for joints &
  • for muscle/tendon/ligament attachment

Openings, Depressions and Projections

2. Categories of Bone Markings

Openings (Holes or Passageways)

These openings allow structures like blood vessels, nerves, and air to pass through bones. Their size and shape reflect the structures they accommodate.

Marking	Description	Example
Foramen	Round passageway through bone	foramen magnum (occipital bone of the skull)
Meatus	Canal or tube-like passageway or opening to a passageway	external auditory meatus (ear canal)
Sinus	Air-filled space in bone	nasal sinus (skull)

Depressions (Grooves or Shallow Areas)

These are indentations or grooves on bone surfaces that can house other structures, such as nerves or muscles. Some serve as articulation sites, while others accommodate soft tissues like vessels or tendons.

Marking	Description	Example
Fossa	A shallow depression in a bone, sometimes made to articulate with another bone	mandibular fossa (temporal bone); olecranon fossa (humerus); iliac fossa (pelvis); acetabulum (hip socket)
Sulcus	Narrow groove or furrow on bone surface that usually accommodates blood vessels, nerves or a tendon	intertubercular sulcus (humerus)

Projections (Bones for Joints or Muscle Attachments)

These are raised areas where bones meet to form joints or where muscles/tendons/ligaments attach.

1. Projections for Forming Joints.

These projections help two bones meet and form movable joints. The surfaces are shaped to fit together—such as rounded heads or flat facets—to allow movement and articulation.

Marking	Description	Example
Head	Expanded end of bone supported by neck that articulates with another bone	head of femur, humerus & rib
Facet	Small flat smooth surface allowing bones to glide on at a joint	superior and inferior articular facets (vertebrae); Facet for rib articulation (thoracic vertebrae)
Condyle	Smooth rounded articular process that means knuckle	mandibular condyle; femur condyle; distal condyle (capitulum + trochlea) of humerus

B. Projections for Muscle, Tendon, or Ligament Attachments

These are raised areas or processes that protrude from the bone surface. They serve as attachment points for muscles, tendons, and ligaments. Their size and shape often reflect the strength and direction of the forces applied to the bone.

Marking	Description	Example
Epicondyle	Prominence above a condyle	medial & lateral epicondyles (humerus)
Spine	Sharp, pointed slender process	ischial spine (pelvis); spinous process (vertebrae)
Trochanter	Broad, flattened & rough process	greater & lesser trochanters (only on femur)
Tubercle	Small, rounded process for muscle attachment	greater & lesser tubercles (humerus); tubercle (rib)
Tuberosity	Rough, large elevated surface for muscle attachment (big bump)	deltoid tuberosity (humerus); ischial tuberosity (pelvis); tibial tuberosity
Crest	Ridge-like structure projecting from the surface or border of a bone	iliac crest (pelvis)

Explore bone markings in 3D!

Test Your Knowledge

Attributions

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